Device for readying a needle free injector for delivery

ABSTRACT

A needle-free injector device comprising a latch having a safe position which disables the triggering of the device, and a ready position which restrains movement of a dispensing member but enables triggering and a triggered position which permits movement of the dispensing member is disclosed. An additional safety mechanism blocks the triggering of the device until removed. A cap is provided to maintain the sterility and stability of the drug formulation and is configured such that the cap removal is required prior to placing the device in a ready to trigger state.

BACKGROUND OF THE INVENTION

Needle-free injectors are used as an alternative to needle-typehypodermic injectors for delivering liquid drugs and other substancesthrough the skin and into the underlying tissue. The drug is dispensedby a piston from a drug capsule at pressures high enough to pierce theskin. Typically, the drug capsule will comprise a hollow cylindricalchamber narrowing to a discharge orifice at one end, with the pistonslidingly and sealingly located at the other. The piston is driventowards the orifice to dispense the drug by a dispensing member.Typically devices are powered by a variety of means, such as a spring(the spring force being supplied by a resilient element or a pressurisedgas) or pyroteclmic charge. Examples of such devices are described inU.S. Pat. Nos. 5,891,086 and 5,480,381

For spring powered needle-free injectors, the spring constantly exerts aforce on the dispensing member prior to use and a restraining means isrequired to prevent the dispensing member from moving under the force ofthe spring. The needle-free injector is triggered by moving the injectorinto a condition in which the restraining means no longer has arestraining effect, thus permitting the dispensing member to move.

It is often desirable for the triggering of the delivery of themedication to involve a very modest force, for example by the patientpressing a button or pressing the injector against the injection site.However, this low force can cause premature triggering, such as when thedevice is dropped, or when the cap over the injection orifice thatmaintains formulation stability and sterility on storage is removed.

A problem exists during the assembly of such devices-producing a devicewhich is easy to operate, may result in a device which is also easy toaccidentally trigger during manufacture and assembly. This is bothwasteful and can be a safety hazard to the personnel involved.

WO 97/37705 addressed this issue by providing a device for dispensing amaterial or article, which comprises a spring, which provides an energystore, a dispensing member movable to effect dispensing under the forceof the spring, latch means having a first position which preventstriggering of the device, a second position in which it restrainsmovement of the dispensing member but enables triggering, and a thirdposition in which it permits such movement, trigger means operable bythe user for moving the latch means from said second position to saidthird position, the first position being a safety mechanism effectivebefore the device has been completely assembled to prevent movement ofthe latch means to the third position.

For the embodiments of the inventions disclosed in WO 97/37705, thesafety mechanism is disengaged at the end of the assembly process, usinga tool inserted into the device to move the latch from the firstposition to the second position, with the latch being restrained frommoving to the third position by an outer-ring. The triggering means,which functions by moving the latch so that it is no longer restrainedby the outer-ring, is then restricted from operating by a tear-off band,which physically stops the movement of the latch with respect to theouter ring, the band being removed prior to triggering the device.

As an alternative to the above, it may be advantageous to store thedevices in the first position, with the original safety mechanismengaged. The devices are stored for up to three years before use andfrom both a general safety and device performance perspective there areadvantages to keeping the safety mechanism engaged. Then followingstorage, just prior to triggering, an attachment to the device is usedto disengage the safety mechanism.

In addition, the orifice must be kept sealed during storage to ensurestability and sterility of the drug product. The removal of the orificeseal is preferably combined with the disengagement of the safetymechanism, to ensure the system is easy to use, and to ensure that theorifice seal is removed prior to the disengagement of the safetymechanism, so that it is not possible that the act of removing theorifice seal triggers the delivery of the drug.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a device forreadying a needle free injector for delivery. The injector comprises aenergy store, such as a pyrotechnic charge, a mechanical spring, orpreferably a pressurized gas spring, and a dispensing member movable, toeffect dispensing, under the force of the spring. The invention providesa cap comprising a seal covering the injection orifice to ensurestability and sterility of the contents, and a mechanism for removingsaid cap. The invention also provides a mechanism for changing the stateof the device from a safe state to a ready to deliver state. The safestate is characterized by an inability to accidentally deliver thecontents, when for example, the device is dropped, the cap is removed,or the device is otherwise affected. The invention also provides for alinkage between the two mechanisms, such that they must be completed inthe correct order, ie the cap is removed while the device is in the safestate.

It is preferred that the act of removing the cap and placing the devicein the ready to deliver state be accomplished in a single motion, forexample by (but not limited to) having a lever, the end of which isattached to the cap, and the base of the lever actuating the safetymechanism. However, it could also be accomplished in two motions, forexample wherein the removal of the cap exposes a safety mechanism whichis subsequently actuated by the user, or alternatively wherein the capis removed, exposing the end of the lever to allow the lever to bepivoted, placing the device in the ready to deliver state.

In one embodiment, the removal of the cap and the placing of the deviceinto the ready state exposes a button, said button being pushed by theuser to deliver the contents. However, it is preferred that the act ofpressing the delivery orifice against the delivery site is what triggersthe device to deliver.

An advantage of the invention is that the cap keeps the contents sterileuntil the delivery

It is another advantage of the invention that the cap maintains thestability of the contents, especially to evaporation.

It is another advantage that the device keeps the injector in the safestate until it is ready to deliver.

It is another advantage that the device ensures that the injector is inthe safe state until after the cap is removed, to ensure that the act ofremoving the cap does not lead to accidental delivery, by for example,accidentally pressing on a trigger button or accidentally pressing theend of the injector in a way that mimics pressing the injector into theskin, causing premature delivery.

These and other advantages will be readily apparent to those skilled inthe art.

In the preferred embodiment, the invention provides a latch means havinga first position wherein the device is safe, and cannot trigger untilthe latch is forcibly moved. The latch also has a second position, whichit restrains movement of the dispensing member, a third position whichreleases the device to cause delivery, and a trigger means operable bythe user for causing the latch means to move from said second positionto said third position. Moreover, there is provided a second safetymechanism which engages and disables the trigger until after the cap hasbeen removed and as the device is placed into the ready to triggerstate. The invention is linked such that it cannot be activated to movethe latch from the first to the second position or disengage the secondsafety mechanism until the cap providing a sterile barrier to theformulation within drug capsule has been removed.

These and other objects, advantages, and features of the invention willbecome apparent to those persons skilled in the art upon reading thedetails of the embodiments as more fully described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in conjunction with the accompanying drawings. It isemphasized that, according to common practice, the various features ofthe drawings are not to-scale. On the contrary, the dimensions of thevarious features are arbitrarily expanded or reduced for clarity.Included in the drawings are the following figures:

A number of different embodiments of the invention are described in thefollowing section making reference to the accompanying drawings, inwhich:

FIG. 1 presents a longitudinal cross-section through the preferredembodiment of the invention;

FIGS. 2 a, b and c show the latch 6 and dispensing member 2 part of theinjector from FIG. 1 in the three stages ending in triggering. In (a)the latch 6 is in the first, or safe position. In (b) the latch 6 is inthe second position, the non-safety, ready to trigger position. In (c),the latch 6 is in the third position, following triggering;

FIG. 3 illustrates a needle free injector with one embodiment of theattachment for disengaging the safety mechanism;

FIGS. 4 a and b show the latch 6, dispensing member 2 and collar 33components of FIG. 3 with the latch 6 in the first, safe position (a)and the second, ready to trigger position (b) respectively;

FIGS. 5 a and b present end on views of the device in FIG. 3 showing asecond safety mechanism comprising block sections, with the (a) theblock sections 38 engaged and (b) the block sections 38 disengaged;

FIGS. 6 a, b and c illustrate another embodiment of the attachment fordisengaging the safety mechanism (a) with the outer cap 31 in place, (b)with the outer cap 31 inverted to cover the seal carrier 20 and (c) withthe seal carrier 20 snapped off by applying pressure to the outer cap31.

FIGS. 7 a, b, c present the third embodiment of the attachment fordisengaging the safety mechanism (a) with the outer cap 31 in place, (b)with the outer cap 31 removed, removing the seal carrier 20 and (c) onrotating the ring section 39.

FIGS. 8 a and b present a cross-section view of the injector in FIG. 7showing a) the safe position and (b) the ready trigger position; and

FIG. 9 shows the needle-free injector as shown within FIG. 3 but withthe button firing mechanism.

DETAILED DESCRIPTION OF THE INVENTION

Before the present device and method are described, it is to beunderstood that this invention is not limited to particular embodimentsdescribed, as such may, of course, vary. It is also to be understoodthat the terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to be limiting, sincethe scope of the present invention will be limited only by the appendedclaims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassedwithin the invention. The upper and lower limits of these smaller rangesmay independently be included or excluded in the range, and each rangewhere either, neither or both limits are included in the smaller rangesis also encompassed within the invention, subject to any specificallyexcluded limit in the stated range. Where the stated range includes oneor both of the limits, ranges excluding either or both of those includedlimits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present invention, the preferred methodsand materials are now described. All publications mentioned herein areincorporated herein by reference to disclose and describe the methodsand/or materials in connection with which the publications are cited.

It must be noted that as used herein and in the appended claims, thesingular Forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise. Thus, for example, reference to“astorage means” includes a plurality of such storage means and referenceto“the spring” includes reference to one or more springs and equivalentsthereof known to those skilled in the art, and so forth.

The publications discussed herein are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present invention isnot entitled to antedate such publication by virtue of prior invention.Further, the dates of publication provided may be different from theactual publication dates which may need to be independently confirmed.

The embodiments of the invention disclosed are based on Aradigm's(formerly Weston Medical's) Intraject needle-free injector, described inWO 95/03844. FIG. 1 presents a longitudinal section through theIntraject needle-free injector prior to integration with the device ofthe present invention. In FIG. 1, the injection force is provided by acompressed gas spring, which comprises a cylinder 1 enclosed at one endcontaining a gas, typically nitrogen, typically at a pressure between150 and 300 bar. Contained within the cylinder is a dispensing member 2.The end of the dispensing member has a frusto-conical, truncatedcone-portion 3 and a flange 4. There is a double o-ring seal 5 situatedbetween the truncated cone section 3 and the flange 4. Prior totriggering the device, the dispensing member 2 is held in the positionillustrated in FIG. 1 by a latch 6 which sits in a groove in thedispensing member. The upper surface of the groove forms a cam surface7. Consequently, there is force urging the latch to move to the left. Inthe configuration shown in FIG. 1, the latch is restricted from movingby the outer ring 8.

At the lower end of the cylinder 1, there is an outwardly directedflange 9. The cylinder is held in place by crimping the flange 9 toanother outwardly directed flange 10 on the upper end on a coupling 11.The sleeve 8 consists of an upper sleeve portion 12 within which thecylinder is situated, and a lower sleeve portion 13. The lower sleeveportion 13 is connected to the coupling 11 by inter-engaging screwthreads 14 formed on the inner and outer walls of the lower sleeveportion 13 and the coupling respectively 11.

The injector has a cartridge 15 which contains the medicament. In thecartridge there is a piston 16, slidingly and sealingly located therein.The piston 16 may comprise a cylindrical portion containing two largerdiameter ribs, and a frusto-conical portion. The piston 16 is in contactwith the medicament 17 and at the other end of the cartridge 15 there isa discharge orifice 18. Adjacent to the orifice 18 there is an interfaceseal 19 contained within a seal carrier 20. The interface seal 19 isrequired for filling the needle-free device as described inPCT/GB9700889. A stopper 20 a seals the medicament into the capsule.Seal 19, seal carrier 20, and stopper 20 a, comprise the cap that mustbe removed prior to delivery.

To place the device in the ready to deliver state, the cap must besnapped off at the frangible joint 21. This removes the seal 19 andexposes the orifice 18. The trigger blocking mechanism 22, whichprevents the medication cartridge from moving back toward the uppersleeve portion 22, thereby preventing delivery, is removed. Finally,latch 6 must be moved from the first (safe) position, to the second(ready to deliver) position,

The latch 6 is incorporated into a groove in the dispensing member 2—notonly does the groove have a cam surface 7 but also a locking surface 27which is perpendicular to the dispensing member axis and is locatedradially inward of the cam surface 7. Additionally, to access the latch6 there is an opening 28 in the upper sleeve 12, which prior totriggering is aligned with the latch 6.

FIGS. 2 a, b and c illustrate the operation of the safety mechanism.When the latch and dispensing member are initially assembled, the latchoccupies the first (safe) position, as shown in FIG. 2 a. In thisposition, the dispensing member-engaging latch portion 29 is acted on bythe locking surface 27. Frictional force ensures that the latch is heldrigid by the locking surface—typically the dispensing member exerts aforce of at least 100N.

The latch is placed in the second (ready to deliver) position using apin which fits through opening 28 to push the latch in the direction ofthe arrow P into the position shown in FIG. 2 b, (and in FIG. 1). Inthis position the dispensing member engaging latch portion 29 is incontact with the radially inner end of the cam surface 7.

To cause delivery, the orifice 18 is then placed against the skin of thepatient. Practically, this involves holding the device by the uppersleeve 12 portion. The upper sleeve 12 is then moved downwards withrespect to the lower sleeve 13, bringing aperture 25 in the wall of theupper sleeve portion 8 into alignment with the latch 6. The latch thenmoves to the left into the aperture 25, under the force exerted on it bythe cam surface 7 formed in the dispensing member 3 into the positionshown in FIG. 2 c. The injector then delivers.

It is advantageous to have a mechanism that places the device in theready to deliver state in a simple motion or motions. FIG. 3 illustratesone embodiment of the combined needle-free injector plus means fordisengaging the safety mechanism 30. In this Figure, the means fordisengaging the safety mechanism consists of a cap 31 enclosing, andholding rigidly, the seal carrier 20, a lever 32 and a collar 33. Thelever 32 and collar 33 are presented in more detail in FIGS. 4 a and 4b. The lever contains a lip 34 at the far end, over which the cap 31 ispositioned. This ensures that the lever 32 cannot be moved before theouter cap 31 is removed, which in turn ensures that the user cannot movethe latch or disengage the safety mechanism until the cap has beenremoved. The lever 32 is pivoted around the pivot axis 35, with thepivoted surface in contact with injector being a cam surface 36. Theforce required to pivot lever 32 is in the range from about 2N to about30N. The collar 33 contains a pin 37 which extends into the devicethrough the opening 28 in the upper sleeve 12 to impinge on the far sideof the latch 6, see FIG. 4 a. The force required to move the latch is inthe range from about 20N to about 120N. To stop the upper sleeve section12 moving with respect to the lower sleeve section 13, there are blocksections 38 between the upper and lower sleeves, which form part of thecollar 33. The relative position of the block sections 38 with respectto the lever 32 is more clearly presented in the end-on view of thedevice shown in FIG. 5 a.

To deliver the device contents, the cap 31 is removed, exposing theinjection orifice 18. With the outer cap 31 removed, the lip 34 isexposed, enabling the lever 32 to rotate about the pivot axis 35. Onlywhen the outer cap 31 is removed can the lever 32 be rotated. As thelever 32 rotates, the cam surface 36 forces the collar 33 to move in thedirection Q in FIGS. 3, 4 a and 5 b pushing the pin 37 against the latch6. When the lever 32 has rotated through a complete cycle, approximately180° as shown in FIG. 4 b, the latch 6 moves to the second position, asshown in FIG. 2 b. The blocks 38 no longer restrict the movement of theupper sleeve 12 with respect to the lower sleeve 13 and the device cantrigger as described above. The relative movement of the block 38 withrespect to the sleeve section 12 and 13 is seen in the end on viewpresented in FIG. 5 b. By integrating the cap 31 to the lever 32 with aflexible joint at the tip 34, the mechanism can also be configured toensure that the user removes the stopper and sets the safety in a singleaction.

FIG. 9 shows an alternate embodiment from FIG. 3 wherein rather thanusing the blocks 38, the movement of the lever 32 exposes a triggerbutton 42, the trigger button 42 subsequently being pressed by thesubject to delivery the medication.

Another embodiment of the invention is shown in FIGS. 6 a, b and c. InFIG. 6 a the as-received device is presented. To operate the device theouter cap 31 is removed, leaving the seal carrier 20 intact. The outercap 31 is then inverted and placed back over the seal carrier 20, asshown in FIG. 6 b. Pressure is then applied to the outer cap 31 to breakthe frangible seal between the seal carrier and the lower sleeve, asshown in FIG. 6 c. The device is then placed in the ready to deliverstate by rotating the lever 32 as described above and presented in FIGS.4 a and b.

A third embodiment of the invention is shown in FIGS. 7 a, b and c. Thisversion of the attachment for disengaging the safety mechanism consistsof an outer cap 31 covering and holding rigid the seal carrier 20—notshown in FIG. 7 a-, a collar section 39 and a barrel section 40. Theneedle-free device fits within the barrel section 40 upper sleeveportion 12 first, so that the longitudinal axis of the device is alignedwith the longitudinal axis of the barrel section 40. The needle-freedevice is held rigidly within the barrel section 40. The collar section39 fits over and is attached to the barrel 40, so that the collarsection 39 is free to rotate about the axis of the device in a clockwisedirection when the outer cap 31 has been removed. The outer cap 31contains a locking mechanism 41 which locks the collar 39 rigid when thecap 31 is in place. To trigger the device the outer cap 31 is removed,which in turn removes the seal carrier 20, exposing the injectionorifice 8. The collar section 39 is now free to rotate clockwise aboutthe axis of the needle free device. Because the cap 31 is locked intothe collar section 39, this ensures that the user cannot move the latchor disengage the safety mechanism until the cap has been removed soforcing the user to prepare the device in the correct order. There is alip 42 on the collar section 39, which is aligned so that the lip fitsunder the lip of the tear-off band 22. As the collar section rotatesclockwise the tear-off band 22 is torn off, so that after a completerevolution, 360°, the tear-off band 22 is completely removed.Simultaneously the safety mechanism is disengaged. This is illustratedby the cross-sections through the collar section shown in FIGS. 8 a andb. In FIG. 8 a the safety mechanism is engaged—that is the latch is inthe safe position shown in FIG. 2 a. On the inside of the collar sectionthere is a pin 37 which extends into the device through the opening 28in the upper sleeve 12 to impinge on the far side of the latch 6. Thepin is in contact with the inner surface of the collar section. Theinner surface of the ring section is a cam surface 43, so that as thecollar rotates the action of the cam surface pushes the pin against thelatch moving the latch from the safe position to the first position asshown in FIG. 8 b. With the tear-off band 22 removed, the device candeliver as outlined above.

The preceding merely illustrates the principles of the invention. Itwill be appreciated that those skilled in the art will be able to devisevarious arrangements which, although not explicitly described or shownherein, embody the principles of the invention and are included withinits spirit and scope. Furthermore, all examples and conditional languagerecited herein are principally intended to aid the reader inunderstanding the principles of the invention and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the invention as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure. The scope of the presentinvention, therefore, is not intended to be limited to the exemplaryembodiments shown and described herein. Rather, the scope and spirit ofpresent invention is embodied by the appended claims.

1. A needle-free injector comprised of a drug capsule, a compressed gas,a piston and an injector orifice; comprising: a cap covering theinjection orifice of the injector; and a mechanism for changing theinjector from a safe position to a ready position to a triggeringposition; wherein the cap is broken off before the injector is placed inthe ready to deliver state.
 2. The device as claimed in claim 1, whereinthe mechanism for changing the injector from the safe position to theready position comprises a latch and wherein the device furthercomprises a mechanism for moving the latch from a latch safe position toa latch ready position, wherein the mechanism for moving the latchcomprise a pin and a means for actuating the pin, wherein, uponactuating the pin, the pin pushes the latch from the latch safe positionto the latch ready position.
 3. The device as claimed in claim 2,wherein the means for actuating the pin comprises a lever movable from alever safe position to a lever ready position, and a collar at leastpartially encircling the injector, wherein actuating the lever moves thecollar which moves the pin against the latch wherein the latch is movedfrom the latch safe position to the latch ready position.
 4. The deviceas claimed in claim 3, wherein the mechanism for changing the injectorfrom the safe position to the ready position to a triggering position,further comprises: an additional safety mechanism to prevent triggeringof the injector; wherein moving of the lever from the lever safeposition to the lever ready position moves the collar; and wherein theadditional safety mechanism is disengaged when the collar moves underthe action of the lever moving from the lever safe position to the leverready position.
 5. The device as claimed in claim 4, wherein theadditional safety mechanism is configured in a block shape to preventtriggering of the device by blocking the relative movement of componentsthat cause the device to change from the ready position to thetriggering position.
 6. The device as claimed in claim 3, wherein movingof the lever exposes a button, wherein pressing of the button causesdelivery of the injector contents.
 7. The device as claimed in claim 3,wherein the lever is movable only after the cap is removed, whereinrotating the lever places the injector in the ready position.
 8. Thedevice of claim 3, wherein the end of the lever is attached to the cap,and a base of the lever actuates a safety mechanism.
 9. The device ofclaim 3, configured such that when the cap is removed, the end of thelever is exposed, allowing the lever to pivot, thereby placing thedevice in the ready position.
 10. The device as claimed in claim 3,wherein the mechanism for changing the injector from the safe positionto the ready position, further comprises: an additional safety mechanismto prevent triggering of the injector wherein the additional safetymechanism is disengaged when the lever is actuated.